Proof of an explicit formula for a series from Ramanujan's Notebooks via tree functions.

We prove a recent conjecture, due to Vigren and Dieckmann, about an explicit triple sum formula for a series from Ramanujan's Notebooks. We shall give two proofs: the first one is by evaluation and based on the identity [Display omitted] where { n k } is a Stirling number of the second kind, and the second one is combinatorial in nature and by induction. [ABSTRACT FROM AUTHOR]